A set-top box is a device that enables a television set to become a user interface capable of receiving and decoding broadcast signals via phone, cable, satellite, the Internet, or other means of communication. Newer Set-top boxes typically include a Personal Video Recorder (PVR) capability, which additionally can record and playback broadcast signals. PVR lets the viewer watch shows in a time shifted mode so that the viewer can apply VCR-like functionality to live broadcasts. For example, the PVR lets the viewer pause, replay, rewind, fast-forward, or skip over advertising while viewing a live show.
The enhanced set-top box has become increasingly complex. The increase in functionality leads to an increase in the hardware components and interconnections used to implement that functionality. Earlier set-top boxes were designed to support a single tuner with audio, video, and data outputs.
Connections between the various components were more or less fixed in stone. While a simple system with fixed connections works well for simple hardware, it begins to become unwieldy and inadequate when more complicated hardware allows the dynamic configuration of multiple input devices (e.g., tuners, buses, and memory devices) feeding multiple output devices (decoders, memory devices, and buses) simultaneously. If a developer tries to hand-code all possible legal configurations of the hardware devices, the developer will quickly discover that the number of cases becomes very large. Hand-coding all possible configurations is possible but it represents a maintenance nightmare.
Furthermore, hand-coding must be repeated for each new product developed. Thus, it is desired to find a way to more general approach that is flexible and allows for reduced maintenance and re-use of software.